A device which is capable of conversion and control of the current and can alter the values of voltage and current to meet the load requirements being used to power any kind of machine is called a power supply. The main purpose of using the power supply is to match the load requirement of the end equipment perfectly in terms of voltage and current. For the most part, the current must be supplied in a controlled manner along with a precise voltage which is sufficient to transfer the current through the system to avoid any circuit damage and complications. Any change in the input current and anomaly in voltage can lead to a misleading output of the system . For the above-listed reasons, AC-DC power supplies play a vital role in many modern electronics from phone chargers and laptops to desktop computers.
There are mainly two types of AC-DC power supplies in terms of functionality, these are regulated and unregulated. For the most part, power supplies work on the same principle of current conversion to meet the system load requirement. For any regulated power supply, the change of the input voltage and current do not affect the output of the supply hence no change of current and voltage to the system. Unlike unregulated power supplies which are purely dependent on the input. Any small deviation or deflection in the input voltage or current is similarly reflected in the output which is to be supplied to the system. Therefore, it is always recommended to use the regulated power supply for any kind of compact or sensitive circuit, as any small deflection in input can lead to complete circuit malfunction.
An AC-DC power supply is a device designed such that it can take the input of alternating current and can rectify it to direct current making use of the rectification principle. AC to DC power supplies are further categorised to further extend the understanding which is linear and switching.
Linear AC-DC Power Supply
For a linear power supply, the voltage of the input AC is reduced to such an extent that it matches the intended requirement. After the reduction of voltage, the voltage is then rectified by a rectifier and turned into DC as per the required current and voltage. After the conversion to DC, there is a further filtration process which enhances and stabilises the waveform quality. The benefits of this design are greatly reduced ripple and noise making for a very “quiet” EMC solution. Nowadays they are only really used in specific applications requiring extremely low noise such as audio applications.
Switching AC-DC Power Supply
Linear power supplies have been used for the conversion of current, however, more recent advancement has resulted in the introduction of switching power supplies. Which aims to solve the issues related to the conventional linear power rectification process such as regulation and size of the transformer making them large, heavy and bulky. Unlike the linear rectification method the voltage is not reduced in the switching mode power supply, it directly undergoes the process of rectification, ripple and noise is filtered out at the output. A MOSFET of FET is introduced in this design which is capable of converting voltage into a pulse of high frequency. In the final stage the wave of high frequency passes through the rectifier and another filter which has the capability for conversion of this wave directly to the DC. The second stage rectifier and filter are responsible for the screening of the DC output and they possess the capability to eliminate the remainder of alternating current. This method allows the device to be much more efficient, making it more power dense allowing for a much smaller device, which makes switching power supplies much more desirable in todays modern market.
Power supply designers can select from a variety of topologies depending on power range, complexity, flexibility, technology and feature set required ranging from low cost fly back to LLC Half Bridge to LLC resonant converter including an active PFC Boost converter. The later two utlising Zero Voltage Switching optimising efficiency further while reducing end system running costs and carbon footprint.
Components Bureau offer a range of AC to DC power supplies from 3W to 30kW. All units are designed and approved for use in industrial applications such as medical, instrumentation, transportation, military, ITE, scientific instruments, and fabrication.
By partnering with top leading manufacturers including Cosel, Cincon, Artesyn, Meanwell and Minmax we consistently deliver the very best solution from a full suite of open-frame, enclosed, encapsulated, external including desktop and plug top, DIN rail and Modular. These can be configured in-house in our UL-approved facility for rapid delivery. Options include low noise, high efficiency, and high reliability.
For unrivalled technical and commercial engineering support please contact us today on 01480 412233 to see how we can help you find the perfect power conversion solution.